Glossary of Biology 101 exam 4 (FINAL)

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Created by jkadlik

• use or defense of a resource by one individual that reduces the availability of that resource to other individuals
• can be intraspecific (within species) or interspecific (between species)
– intraspecific competition is most intense; members of same species consume the same resources

Competitive exclusion
• two species cannot coexist on the same limiting resource,
– two species with identical resource requirements cannot coexist.
– close inspection of similar species generally reveals differences in food and/or habitat preferences,

Between-species competition, summary
• Common interaction, but extensive niche overlap (direct competition) infrequently observed
– most likely to see it when species newly introduced or when other factors limit population of better competitor
• Instead, known mostly by its consequences (outcomes)

Species interactions in communities
• Each species interacts with many other species.
• Communities include complex webs of interactions among many species.
• Connections often revealed by unexpected outcomes when communities are disrupted.

Community dynamics revealed by disruptions

• Two examples:
– forest cut  vertebrate diseases increase
– sea otters decline kelp forests disappear

Minimum Critical Size of Ecosystems Project: one result
• in small fragments, some bird and mammal species disappear
• less dung and carrion • scarab beetles become scarce • mites that infest beetles become scarcer • fewer mites means more flies • more flies means pathogens spread more rapidly
Number of species on Island determined by

Immigration Rate : Species Added Extinction Rate : Species Subtracted
Sea otters and kelp forests
• uneven recovery of otter populations allowed a comparison:
– otters present: kelp forest community
– otters absent: no kelp • What’s the connection?
– sea urchins – urchins graze on kelp – otter predation limits urchin populations

keystone species

• a species whose importance to community is great, relative to its abundance
– often identified when removed

exotic species...
• species introduced by humans to communities in which they were not previously found.
• introduction can be intentional or unintentional
• have affected virtually all communities, but especially problematic in disrupted habitats.
• exotics often invasive

Characteristics of Invasives
• Rapid Population Growth
• Displace or Kill Native Species
• No natural population regulation
– No predators
– No pathogens
• High Dispersal Rates

Why are exotics such strong competitors?
• Study of European plant (473) and animal (26) species that have invaded U.S.
• Compared parasites in both locales. – 84% drop in fungal infections (plants) – 24% drop in viral infections – Overall 77% lower disease rate
Nitrogen Cycle
•Includes major atmospheric pool - N2. (80%) Only nitrogen fixers can use atmospheric supply directly.
•Energy-demanding process. N2 reduced to ammonia (NH3).
•Once N is fixed it is available to plants.
•Upon death of an organism, N can be released by fungi and bacteria during decomposition.

Nitrogen fixing bacteria
convert N2 to Ammonium (NH4+)
Nitrifying bacteria
convert Ammonium (NH4+) to Nitrites (NO2-) and Nitrates (NO3-), that plants can assimilate.
Denitrifying bacteria
convert Nitrates (NO3-) to N2
Disruption of the nitrogen cycle
•deforestation transfers nitrogen from terrestrial to aquatic ecosystems
•manufacture of fertilizer fixes huge additional amounts of nitrogen, which ends up in aquatic ecosystems
• farming transfers nitrogen to sewage (people and factory-farm animals), which ends up in aquatic ecosystems.
• Burning fossil fuels releases nitrogen that is deposited in precipitation and as solid particles.

• Steep Sided, Clear Water
• Low Nutrient Enrichment
• Little Planktonic Growth, Low Productivity
• Few Aquatic Plants
• Sand or Rock Along Most of Shoreline
• Coldwater Fishery
• High Dissolved Oxygen Content

• Moderate Nutrient Enrichment
• Moderate Planktonic Growth
• Some Sediment Accumulation Over Most of Lake Bottom
• Usually Supports Warm-water Fish Species

• High Nutrient Enrichment
• Much Planktonic Growth (High Productivity)
• Extensive Aquatic Plant Beds
• Much Sediment Accumulation on Lake
• Low Bottom Dissolved Oxygen
• Only Warmwater Fish Species

Are dead zones natural?
Yes and no.
Their geographic distribution, size, and persistence has increased in connection with increased anthropogenic increases in nutrient loading.
Carbon Cycle
• Atmosphere contain large sink of C as CO2
• Plants absorb CO2 and via photosynthesis convert it to
• Animals metabolize carbohydrates and release C as CO2
• Sea surface absorbs and releases CO2 into atmospheric
• Marine organisms use C to build their bodies. In addition
C cycles through oceans in several forms.
• Carbon is sequestered as fossil fuels and in ocean
• Humans release stored C by burning fossil fuels and cutting down forests.

Carbon Cycle- key points
• Carbon cycles through several compartments
– Atmosphere
– Oceans
– Biological
– Geological
• Some carbon is sequestered into sinks
• Humans are releasing carbon from geological sink faster then it is returned and can be absorbed by oceans.

How do we know the CO2 is from human activity?
1) Correlation between CO2 increase and increase in use of fossils fuels.
2) Isotope signature of atmospheric CO2.
Isotopic signature of CO2 from fossil fuels
• Plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C/12C ratios.
• Since fossil fuels are ultimately derived from ancient plants, plants and fossil fuels all have roughly the same 13C/12C ratio – about 2% lower than that of the atmosphere.
• As CO2 from these materials is released into, and mixes with, the atmosphere, the average 13C/12C ratio of the atmosphere decreases.

CO2 Summary
• The amount of CO2 in the atmosphere is determined by the net movement of C in and out of various compartments.
• Humans are currently releasing C for long- term sinks at a rate greater than it is sequestered into terrestrial and marine sinks.
• Once in the atmosphere CO2 levels take 100’s of years to return to previous levels.

Has global warming stopped?

• Short term trends
• Arbitrary start points
• Focus on regional data
• About 85% of hottest years since 1850 have been during the last decade.
• Ocean heat content shows rapid rate of increase.

Radiative Forcings
Radiative forcing is a factor that changed in the balance between radiation coming into the atmosphere and radiation going out.
Radiative forcings & feedbacks*
• Positive
– Greenhouse gases (CO2, methane, etc.)
– Tropospheric ozone
– Solar radiation
– Black carbon on snow
– Water vapor*
– Albedo*
- loss of sea ice and snow cover
• Negative
– Aerosols (clouds* and industrial aerosols)
– Albedo
- Landuse

Why is water vapor a feedback?
CO2 forcing causes water vapor feedback
• Increase CO2
• Increase global temperature
• Increase water vapor
• Increase global temperature
• In addition, water vapor has very short retention time.

Does the amount of energy input from the sun change over time?

Milankovitch and Ice Age cycles
Change in solar radiation caused by Milankovitch cycles enough to trigger interglacial warming.
But, not enough to explain most of warming. Only increases in CO2 can explain remainder of change.
Fingerprints of Anthropogenic Global Warming
• Lower layer of atmosphere warmed, upper cooled.
• Middle of continents warmed more then middle of oceans.
• Low latitudes warmed less then high.
• Night warmed more then day.
• Models can not account for warming with out human added CO2

Geographic Pattern of Warming
• Greater warming at poles
• Greater warming in northern hemisphere
• Greater warming at center of continents

General Circulation Models
• Physical models - not statistical
• Model planet as cubes from surface up into upper atmosphere.
• Physical processes that determine changes in temperature are simulated within and between adjacent cubes

What causes sea level rise?
1) Thermal expansion of water
2) Melting Ice Caps and glaciers
How will sea level rise impact coastal areas?
1) Alteration and loss of coastal marches and estuaries.
2) Erosion of coastal habitats.
3) Further penetration of storm surge into fresh water ecosystems during tropical cyclones.

Model Evaluation
• Hindcasting
o Looking at how accurate the model is in the past
• Running the model with and without anthropogenic CO2
• Impacts of major volcanic eruption

Uncertainty in Model Predictions
• Regional> Continental> Global
• Seasonal> Yearly > Decade Average
• Model sensitivity- how much will it warm for doubling of CO2 (1.5 degrees to 4.5 degrees, with 3 degrees most likely)

Snow pack
• If there is less snow pack, there will be less water for the streams, and will therefore run dry much earlier
• Increase in wildfires with less snow pack

Tropical Cyclones
1) Fewer storms
2) More Cat 4 and 5 storms and fewer weaker storms.
Controlling Invasives
• Block entry
o Black list
o White list
• Burn, pull or poison
• Biological Control
o Introduce predator
o Introduce disease
o Breed sterile individuals

Describe the yearly cycle of climate on Barro Colorado Island
• Has a dry and wet season

What is the name of the giant forest tree?
• Dipteryx Tree

Describe the chain of interactions that are required for this tree to reach maturity. Include aspects of both physical and natural environment (animals) that are part of this chain
• The Dipteryx tree has fruit during the dry season, and the fruit bats carry the fruit to the same spot far away from the tree to eat at night. In the morning agouti will find the pile of half eaten fruit, eat some, then bury the rest
• Fruit bats are scared away by snakes, and the fruit bats eat they’re fruit far away from the tree. The agouti and other rodents bury the excess seeds.

Describe how the Tungara frog call system has evolved to balance the forces of sexual selection (shaping the call to make it more attractive to females) and natural selection (shaping the call system to make it less attractive to predators)
• If the frogs calls are too loud and frequent , they’ll be eaten, but if they aren’t loud or frequent enough they wont mate
• Whine when alone, but if females are near they add a chuck. This chuck encodes information about the males size. Chucking attracts predators though

Describe the mutualism that evolved between “calling caterpillars” and ants
• Ants are found on acacia plant, and ants protect the acacia plant
• Acacia plant provides nectar to ants
• Ants guard acacia
• Caterpillar has nectar organ to feed ants
• Ants guard caterpillar and let it feed on acacia
• Caterpillars alarm calls to ants defense

Ocean Acidification
Increasing CO2 in atmosphere increases concentration of CO2 in oceans.
CO2 + H2O= Carbonic Acid
This increases ocean acidity (pH) and decreases carbonate.
Calcium + carbonate Calcium carbonate the principle ingredient of shells and coral. Less available for animals who create shells

Does increases in ocean acidity have an affect?
• Areas of ocean that naturally have lower pH, have fewer organisms that have structures made of calcium carbonate.
• Parts of the ocean that have acidified the most have shown shifts in the composition o plankton species.
• Reefs where pH has declined have exhibited coral thinning.

Increasing temp effect on plants
Increasing temperatures can make an area either less or more suitable for a given species.
Altitudinal Shifts
• Majority of North American birds have shifted ranges to the north in last 30 years. 2.35 kilometers/year
• Majority of British Birds have shifted ranges to north.
• Wide geographic distribution of patterns implicates climate change.

Biological responses to global warming
• Ecophysiological
– General Model
– Responses to physiological stress
o Local extinction
o Adaptation
o Dispersal
• Live cycle timing
– Dispersal and migration
– Cycles of activity and dormancy
– Reproduction

Egg Laying Dates
• Migrate earlier
• Lay eggs earlier
• Response of Insect Prey
• Prey availability and reproductive timing may be out of sync.
• Birds can respond by
– No response and population decline
– Acclimate and learn to breed in sync
– Population evolves to breed in sync

Types of Dispersal


Which species are most likely to adapt?

Those with short generation times - 2 years or less.

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